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1.
J Biomech Eng ; 145(2)2023 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-36082481

RESUMO

Thrombosis and intimal hyperplasia have remained the major failure mechanisms of small-diameter vascular grafts used in bypass procedures. While most efforts to reduce thrombogenicity have used a biochemical surface modification approach, the use of local mechanical phenomena to aid in this goal has received somewhat less attention. In this work, the mechanical, fluid transport, and geometrical properties of a layered and porous vascular graft are optimized within a porohyperelastic finite element framework to maximize self-cleaning via luminal reversal fluid velocity (into the lumen). This is expected to repel platelets as well as inhibit the formation of and/or destabilize adsorbed protein layers thereby reducing thrombogenic potential. A particle swarm optimization algorithm was utilized to maximize luminal reversal fluid velocity while also compliance matching our graft to a target artery (rat aorta). The maximum achievable luminal reversal fluid velocity was approximately 246 µm/s without simultaneously optimizing for host compliance. Simultaneous optimization of reversal flow and compliance resulted in a luminal reversal fluid velocity of 59 µm/s. Results indicate that a thick highly permeable compressible inner layer and a thin low permeability incompressible outer layer promote intraluminal reversal fluid velocity. Future research is needed to determine the feasibility of fabricating such a layered and optimized graft and verify its ability to improve hemocompatibility.


Assuntos
Modelos Cardiovasculares , Enxerto Vascular , Animais , Artérias , Prótese Vascular , Complacência (Medida de Distensibilidade) , Ratos
2.
Neuromodulation ; 26(3): 681-689, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37032583

RESUMO

OBJECTIVES: Fatigue is one of the most important symptoms needing improvement in Primary Sjögren's syndrome (PSS). Previous data from our group suggest that noninvasive stimulation of the vagus nerve (nVNS) may improve symptoms of fatigue. This experimental medicine study uses the gammaCore device (electroCore) and a sham device to investigate the relationship between nVNS and fatigue in PSS, and to explore potential mechanisms involved. MATERIALS AND METHODS: Forty participants with PSS were randomly assigned to use active (n = 20) or sham (n = 20) nVNS devices twice daily for 54 days in a double-blind manner. Patient-reported measures of fatigue were collected at baseline and day 56: Profile of Fatigue (PRO-F)-Physical, PRO-F-Mental and Visual Analogue Scale of abnormal fatigue (fVAS). Neurocognitive tests, immunologic responses, electroencephalography alpha reactivity, muscle acidosis, and heart rate variability were compared between devices from baseline to day 56 using analysis of covariance. RESULTS: PRO-F-Physical, PRO-F-Mental, and fVAS scores were significantly reduced at day 56 in the active group only (p = 0.02, 0.02, and 0.04, respectively). Muscle bioenergetics and heart rate variability showed no change between arms. There were significant improvements in digit span and a neurocognitive test (p = 0.03), and upon acute nVNS stimulation, frontal region alpha reactivity showed a significant negative relationship with fatigue scores in the active group (p < 0.01). CONCLUSIONS: We observed significant improvements in three measures of fatigue at day 56 with the active device but not the sham device. Directly after device use, fatigue levels correlate with measures of alpha reactivity, suggesting modulation of cholinergic system integrity as a mechanism of action for nVNS.


Assuntos
Fadiga , Síndrome de Sjogren , Estimulação do Nervo Vago , Humanos , Fadiga/diagnóstico , Fadiga/etiologia , Fadiga/terapia , Medição da Dor , Síndrome de Sjogren/complicações , Síndrome de Sjogren/terapia , Resultado do Tratamento , Estimulação do Nervo Vago/métodos
3.
J Surg Res ; 269: 165-170, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34563843

RESUMO

BACKGROUND: With the onset of the COVID-19 pandemic and subsequent widespread stay-at-home advisories throughout early 2020, hospitals have noticed a decrease in illnesses unrelated to COVID-19. However, the impact on traumatic injury is relatively unknown. This study aims to characterize patterns of trauma during the COVID-19 pandemic at a Level I Trauma Center. MATERIALS & METHODS: A retrospective review was performed of adult trauma patients from March to June, in the years 2018 through 2020. Primary outcome was the number of trauma activations (volume). Secondary outcomes included activation level, mechanism of injury, mortality rate, and length of stay, and other demographic background. Trauma patterns of the 2018 and 2019 periods were combined as historical control, and compared to patterns of the biweekly-matched period of 2020. RESULTS: A total of 2,187 patients were included in analysis (Pre-COVID n = 1,572; COVID n = 615). Results were significant for decreased trauma volume but longer length of stay during COVID cohort, and for an increased proportion of males. No significant difference was found for other demographic variables, trauma mechanisms, or severity. Trauma volume patterns mirrored COVID rates in the state. CONCLUSIONS: Despite a decline in trauma volume, other trauma patterns including severity and mechanism remained unchanged during the COVID-19 period. The decreased volume was not associated with a markedly lower clinical workload, change in team structure, or provider coverage re-distribution. Our data suggests that trauma volume and severity remained high enough during COVID-19 peak to necessitate full staffing, which may provide guidance in the event of a pandemic resurgence.


Assuntos
COVID-19 , Centros de Traumatologia/estatística & dados numéricos , Ferimentos e Lesões/epidemiologia , Adulto , COVID-19/prevenção & controle , Controle de Doenças Transmissíveis , Feminino , Humanos , Masculino , New England/epidemiologia , Pandemias , Estudos Retrospectivos
4.
J Headache Pain ; 23(1): 12, 2022 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-35062860

RESUMO

BACKGROUND: Noninvasive vagus nerve stimulation (nVNS) has recently emerged as a promising therapy for migraine. We previously demonstrated that vagus nerve stimulation inhibits cortical spreading depression (CSD), the electrophysiological event underlying migraine aura and triggering headache; however, the optimal nVNS paradigm has not been defined. METHODS: Various intensities and doses of nVNS were tested to improve efficacy on KCl-evoked CSD frequency and electrical threshold of CSD in a validated rat model. Chronic efficacy was evaluated by daily nVNS delivery for four weeks. We also examined the effects of nVNS on neuroinflammation and trigeminovascular activation by western blot and immunohistochemistry. RESULTS: nVNS suppressed susceptibility to CSD in an intensity-dependent manner. Two 2-minute nVNS 5 min apart afforded the highest efficacy on electrical CSD threshold and frequency of KCl-evoked CSD. Daily nVNS for four weeks did not further enhance efficacy over a single nVNS 20 min prior to CSD. The optimal nVNS also attenuated CSD-induced upregulation of cortical cyclooxygenase-2, calcitonin gene-related peptide in trigeminal ganglia, and c-Fos expression in trigeminal nucleus caudalis. CONCLUSIONS: Our study provides insight on optimal nVNS parameters to suppress CSD and suggests its benefit on CSD-induced neuroinflammation and trigeminovascular activation in migraine treatment.


Assuntos
Depressão Alastrante da Atividade Elétrica Cortical , Transtornos de Enxaqueca , Estimulação do Nervo Vago , Animais , Cefaleia , Transtornos de Enxaqueca/terapia , Doenças Neuroinflamatórias , Ratos
5.
Neuromodulation ; 22(5): 580-585, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30328647

RESUMO

OBJECTIVES: Primary Sjögren's syndrome (pSS) sufferers have rated chronic fatigue as the most important symptom needing improvement. Emerging data suggest that stimulation of the vagus nerve can modulate immunological responses. The gammaCore device (electroCore), developed to stimulate the cervical vagus nerve noninvasively, was used to assess the effects of vagus nerve activation on immune responses and clinical symptoms of pSS. MATERIALS AND METHODS: Fifteen female pSS subjects used the nVNS device twice daily a 26-day period. At baseline, blood was drawn before and after application of the gammaCore device for 90 sec over each carotid artery. The following fatigue-related outcome measures were collected at baseline, day 7 and day 28: EULAR patient reported outcome index, profile of fatigue (Pro-F), visual analogue scale of abnormal fatigue, and Epworth sleepiness scale (ESS). Whole blood samples were stimulated with 2 ng/mL lipopolysaccharide (LPS) and the supernatant levels of IFNγ, IL12-p70, TNFα, MIP-1α, IFNα, IL-10, IL-1ß, IL-6, and IP-10 were measured at 24 hours. In addition, clinical hematology and flow cytometric profiles of whole blood immune cells were analyzed. RESULTS: Pro-F and ESS scores were significantly reduced across all three visits. LPS-stimulated production of IL-6, IL-1ß, IP-10, MIP-1α, and TNFα were significantly reduced over the study period. Patterns of NK- and T-cell subsets also altered significantly over the study period. Interestingly, lymphocyte counts at baseline visit correlated to the reduction in fatigue score. CONCLUSION: The vagus nerve may play a role in the regulation of fatigue and immune responses in pSS and nVNS may reduce clinical symptoms of fatigue and sleepiness. However, a sham-controlled follow-up study with a larger sample size is required to confirm the findings.


Assuntos
Fadiga/imunologia , Fadiga/terapia , Imunidade Celular/fisiologia , Síndrome de Sjogren/imunologia , Síndrome de Sjogren/terapia , Estimulação do Nervo Vago/métodos , Adulto , Idoso , Fadiga/sangue , Feminino , Humanos , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Pessoa de Meia-Idade , Síndrome de Sjogren/sangue , Linfócitos T/imunologia , Linfócitos T/metabolismo , Resultado do Tratamento , Estimulação do Nervo Vago/tendências
6.
Neuromodulation ; 22(5): 564-572, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30288866

RESUMO

OBJECTIVES: The primary objective of this study was to explore the impact of noninvasive Vagal Nerve Stimulation (nVNS) on brain electrophysiology, as assessed through spontaneous resting-state EEG and stimulus-driven event-related potentials (ERPs). METHODS: A hand-held transcutaneous stimulator was placed on the neck over the main branch of the left vagus (active condition) or more laterally over neck muscles (sham condition), with two 120-sec long bursts of stimulation applied over a five-minute period. For each of eight neurotypical subjects, prior to stimulation, and then again beginning at 15, 120, and 240 min post-stimulation, ten minutes of background EEG data were collected, along with a series of ERPs-N100 auditory sensory-gating; the N1/P2 loudness dependent auditory evoked responses (LDAER); mismatch negativity; P300a; and P300b. Each subject participated in active and sham stimulation sessions. RESULTS: Brief nVNS had a significant (p < 0.05), and in some cases prolonged (>2 hours), impact on the spontaneous EEG (decreased theta and alpha, and increased beta and gamma), and on sensory gating, LDAER, and P300b evoked responses. Based on prior literature, these specific observations may reflect nVNS-induced modulation of particular neurotransmitter systems including those for GABA (gamma power and frequency); acetylcholine (sensory gating); serotonin (LDAER); and noradrenaline (P300b). CONCLUSIONS: Brief nVNS leads to changes in a sub-set of resting-state and event-related electrophysiologic indices of brain activity. These changes are believed to be mediated by vagal afferent projections to the nucleus of the solitary tract, which in turn regulates several neurotransmitter systems through known direct and indirect neuroanatomic pathways.


Assuntos
Encéfalo/fisiologia , Eletroencefalografia/métodos , Potenciais Evocados/fisiologia , Estimulação do Nervo Vago/métodos , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação do Nervo Vago/instrumentação , Adulto Jovem
7.
Neuromodulation ; 21(3): 261-268, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29076212

RESUMO

OBJECTIVES: To develop the first high-resolution, multi-scale model of cervical non-invasive vagus nerve stimulation (nVNS) and to predict vagus fiber type activation, given clinically relevant rheobase thresholds. METHODS: An MRI-derived Finite Element Method (FEM) model was developed to accurately simulate key macroscopic (e.g., skin, soft tissue, muscle) and mesoscopic (cervical enlargement, vertebral arch and foramen, cerebral spinal fluid [CSF], nerve sheath) tissue components to predict extracellular potential, electric field (E-Field), and activating function along the vagus nerve. Microscopic scale biophysical models of axons were developed to compare axons of varying size (Aα-, Aß- and Aδ-, B-, and C-fibers). Rheobase threshold estimates were based on a step function waveform. RESULTS: Macro-scale accuracy was found to determine E-Field magnitudes around the vagus nerve, while meso-scale precision determined E-field changes (activating function). Mesoscopic anatomical details that capture vagus nerve passage through a changing tissue environment (e.g., bone to soft tissue) profoundly enhanced predicted axon sensitivity while encapsulation in homogenous tissue (e.g., nerve sheath) dulled axon sensitivity to nVNS. CONCLUSIONS: These findings indicate that realistic and precise modeling at both macroscopic and mesoscopic scales are needed for quantitative predictions of vagus nerve activation. Based on this approach, we predict conventional cervical nVNS protocols can activate A- and B- but not C-fibers. Our state-of-the-art implementation across scales is equally valuable for models of spinal cord stimulation, cortex/deep brain stimulation, and other peripheral/cranial nerve models.


Assuntos
Simulação por Computador , Modelos Neurológicos , Estimulação do Nervo Vago , Análise de Elementos Finitos , Humanos
8.
J Neurochem ; 2017 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-29266221

RESUMO

Chronically activated microglia contribute to the development of neurodegenerative diseases such as Alzheimer's disease (AD) by the release of pro-inflammatory mediators that compromise neuronal function and structure. Modulating microglia functions could be instrumental to interfere with disease pathogenesis. Previous studies have shown anti-inflammatory effects of acetylcholine (ACh) or norepinephrine (NE), which mainly activates the ß-receptors on microglial cells. Non-invasive vagus nerve stimulation (nVNS) is used in treatment of drug-resistant depression, which is a risk factor for developing AD. The vagus nerve projects to the brainstem's locus coeruleus from which noradrenergic fibers reach to the Nucleus Basalis of Meynert (NBM) and widely throughout the brain. Pilot studies showed first signs of cognitive-enhancing effects of nVNS in AD patients. In this study, the effects of nVNS on mouse microglia cell morphology were analyzed over a period of 280 min by 2-photon laser scanning in vivo microscopy. Total branch length, average branch order and number of branches, which are commonly used indicators for the microglial activation state were determined and compared between young and old wild-type and amyloid precursor protein/presenilin-1 (APP/PS1) transgenic mice. Overall, these experiments show strong morphological changes in microglia, from a neurodestructive to a neuroprotective phenotype, following a brief nVNS in aged animals, especially in APP/PS1 animals, whereas microglia from young animals were morphologically unaffected.

9.
Neurobiol Dis ; 102: 96-104, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28286178

RESUMO

Vagus nerve stimulation (VNS) has been reported to be effective in the abortive treatment of both migraine and cluster headache. Using validated animal models of acute dural-intracranial (migraine-like) and trigeminal-autonomic (cluster-like) head pain we tested whether VNS suppresses ongoing and nociceptive-evoked firing of trigeminocervical neurons to explain its abortive effects in migraine and cluster headache. Unilateral VNS was applied invasively via hook electrodes placed on the vagus nerve. A single dose of ipsilateral or contralateral VNS, to trigeminal recording and dural-stimulating side, suppressed ongoing spontaneous and noxious dural-evoked trigeminocervical neuronal firing. This effect was dose-dependent, with two doses of ipsilateral VNS prolonging suppression of ongoing spontaneous firing (maximally by ~60%) for up to three hours, and dural-evoked (Aδ-fiber; by ~22%, C-fiber: by ~55%) responses for at least two hours. Statistically, there was no difference between ipsilateral and contralateral groups. Two doses of VNS also suppressed superior salivatory nucleus-evoked trigeminocervical neuronal responses (maximally by ~22%) for 2.5h, to model nociceptive activation of the trigeminal-autonomic pathway. VNS had no effect on normal somatosensory cutaneous facial responses throughout. These studies provide a mechanistic rationale for the observed benefits of VNS in the abortive treatment of migraine and cluster headache. In addition, they further validate these preclinical models as suitable approaches to optimize therapeutic efficacy, and provide an opportunity to hypothesize and dissect the neurobiological mechanisms of VNS in the treatment of primary headaches.


Assuntos
Cefaleia/fisiopatologia , Cefaleia/terapia , Neurônios/fisiologia , Núcleos do Trigêmeo/fisiopatologia , Estimulação do Nervo Vago , Potenciais de Ação , Animais , Pressão Sanguínea/fisiologia , Modelos Animais de Doenças , Dura-Máter/fisiopatologia , Eletrodos Implantados , Lateralidade Funcional/fisiologia , Masculino , Dor Nociceptiva/fisiopatologia , Dor Nociceptiva/terapia , Distribuição Aleatória , Ratos Sprague-Dawley , Estimulação do Nervo Vago/métodos
10.
Neuromodulation ; 19(3): 283-90, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26990318

RESUMO

OBJECTIVES: The purpose of this study was to test the transcutaneous noninvasive vagus nerve stimulator (nVNS) (gammaCore©) device to determine if it modulates the peripheral immune system, as has been previously published for implanted vagus nerve stimulators. MATERIALS AND METHODS: A total of 20 healthy males and females were randomized to receive either nVNS or sham stimulation (SST). All subjects underwent an initial blood draw at 8:00 am, followed by stimulation with nVNS or SST at 8:30 am. Stimulation was repeated at 12:00 pm and 6:00 pm. Additional blood samples were withdrawn 90 min and 24 hour after the first stimulation session. After samples were cultured using the Myriad RBM TruCulture (Austin, TX) system (WBCx), levels of cytokines and chemokines were measured by the Luminex assay and statistical analyses within and between groups were performed using the Wilcoxon Signed Ranks Test and Mann-Whitney U with the statistical program R. RESULTS: A significant percent decrease in the levels of the cytokine interleukin [IL]-1ß, tumor necrosis factor [TNF] levels, and chemokine, interleukin [IL]-8 IL-8, macrophage inflammatory protein [MIP]-1α, and monocyte chemoattractant protein [MCP]-1 levels was observed in the nVNS group non-lipopolysaccharide (LPS)-stimulated whole blood culture (n-WBCx) at the 24-hour time point (p < 0.05). In SST group, there was a significant percent increase in IL-8 at 90 min post-stimulation (p < 0.05). At 90 min, the nVNS group had a greater percent decrease in IL-8 concentration (p < 0.05) compared to SST group. The nVNS group had a greater percent decrease in cytokines (TNF, IL-1ß) and chemokines (MCP-1 and IL-8) at 24 hour (p < 0.05) in comparison to SST. LPS-stimulated whole blood cultures (L-WBCx) did not show a significant decrease in cytokine levels in either the nVNS or SST group across any time points. The nVNS group showed a significant percent increase in LPS-stimulated IL-10 levels at the 24-hour time point in comparison to SST. CONCLUSIONS: nVNS downregulates inflammatory cytokine release suggesting that nVNS may be an effective anti-inflammatory treatment.


Assuntos
Citocinas/sangue , Regulação para Baixo/fisiologia , Pele/inervação , Estimulação do Nervo Vago/métodos , Adolescente , Adulto , Células Sanguíneas/efeitos dos fármacos , Hemocultura , Relação Dose-Resposta a Droga , Método Duplo-Cego , Feminino , Voluntários Saudáveis , Humanos , Lipopolissacarídeos/farmacologia , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Estatísticas não Paramétricas , Fatores de Tempo , Adulto Jovem
11.
J Headache Pain ; 16: 101, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26631234

RESUMO

BACKGROUND: The debilitating nature of migraine and challenges associated with treatment-refractory migraine have a profound impact on patients. With the need for alternatives to pharmacologic agents, vagus nerve stimulation has demonstrated efficacy in treatment-refractory primary headache disorders. We investigated the use of cervical non-invasive vagus nerve stimulation (nVNS) for the acute treatment and prevention of migraine attacks in treatment-refractory episodic and chronic migraine (EM and CM) and evaluated the impact of nVNS on migraine-associated sleep disturbance, disability, and depressive symptoms. METHODS: Twenty patients with treatment-refractory migraine were enrolled in this 3-month, open-label, prospective observational study. Patients administered nVNS prophylactically twice daily at prespecified times and acutely as adjunctive therapy for migraine attacks. Pain intensity (visual analogue scale [VAS]); number of headache days per month and number of migraine attacks per month; number of acutely treated attacks and time to achieve pain relief; sleep quality (Pittsburgh Sleep Quality Index [PSQI]); migraine disability assessment (MIDAS); depressive symptoms (Beck Depression Inventory(®) [BDI]); and adverse events (AEs) were evaluated. RESULTS: Of the 20 enrolled patients, 10 patients each had been diagnosed with EM and CM. Prophylaxis with nVNS was associated with significant overall reductions in patient-perceived pain intensity (mean VAS scores at baseline vs 3 months: 7.75 ± 0.64 vs 4.05 ± 0.76; 95 % CI: 3.3, 4.1; p < 0.0001), mean number of headache days per month (baseline vs 3 months: 14.7 ± 4.1 vs 8.9 ± 3.66; 95 % CI: 3.3, 8.3; p < 0.0001), and mean number of migraine attacks per month (baseline vs 3 months: 7.3 ± 3.85 vs 4.45 ± 2.48; 95 % CI: 0.8, 4.9; p < 0.01). For acutely treated migraine attacks, a reduction in mean time (minutes) to achieve pain relief (baseline vs 3 months: 84.5 ± 39.1 vs 52.75 ± 16.42; 95 % CI: 12.6, 51.0; p < 0.002) was noted. Significant improvements, more evident in patients with EM, were noted in MIDAS and BDI scores along with a trend toward improvement in PSQI daytime dysfunction subscore (p = 0.07). No severe or serious AEs occurred. CONCLUSION: In this study, treatment with nVNS was safe and provided clinically meaningful decreases in the frequency, intensity, and duration of migraine attacks in patients with treatment-refractory migraine. Improvements in migraine-associated disability, depression, and sleep quality were also noted.


Assuntos
Transtornos de Enxaqueca/epidemiologia , Transtornos de Enxaqueca/prevenção & controle , Medição da Dor/métodos , Transtornos do Sono-Vigília/epidemiologia , Transtornos do Sono-Vigília/prevenção & controle , Estimulação do Nervo Vago/métodos , Adulto , Idoso , Vértebras Cervicais , Doença Crônica , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Resultado do Tratamento
13.
Neurotrauma Rep ; 5(1): 150-158, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38435077

RESUMO

Non-invasive vagus nerve stimulation (nVNS) has recently been suggested as a potential therapy for traumatic brain injury (TBI). We previously demonstrated that nVNS inhibits cortical spreading depolarization, the electrophysiological event underlying migraine aura, and is relevant to TBI. Our past work also suggests a role for interleukin-1 beta (IL-1ß) in cognitive deficits after closed head injury (CHI) in mice. We show that nVNS pre-treatment suppresses CHI-associated spatial learning and memory impairment and prevents IL-1ß activation in injured neurons, but not endothelial cells. In contrast, nVNS administered 10 min after CHI was ineffective. These data suggest that nVNS prophylaxis might ameliorate neuronal dysfunction associated with CHI in populations at high risk for concussive TBI.

14.
Pharm Res ; 30(4): 1147-60, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23224981

RESUMO

PURPOSE: Arterial wall mass transport properties dictate local distribution of biomolecules or locally delivered dugs. Knowing how these properties vary between coronary artery locations could provide insight into how therapy efficacy is altered between arterial locations. METHODS: We introduced an indocarbocyanine drug surrogate to the lumens of left anterior descending and right coronary (LADC; RC) arteries from pigs with or without a pressure gradient. Interstitial fluorescent intensity was measured on live samples with multiphoton microscopy. We also measured binding to porcine coronary SMCs in monoculture. RESULTS: Diffusive transport constants peaked in the middle sections of the LADC and RC arteries by 2.09 and 2.04 times, respectively, compared to the proximal and distal segments. There was no statistical difference between the average diffusivity value between LADC and RC arteries. The convection coefficients had an upward trend down each artery, with the RC being higher than the LADC by 3.89 times. CONCLUSIONS: This study demonstrates that the convective and diffusive transport of lipophilic molecules changes between the LADC and the RC arteries as well as along their length. These results may have important implications in optimizing drug delivery for the treatment of coronary artery disease.


Assuntos
Carbocianinas/farmacocinética , Vasos Coronários/metabolismo , Corantes Fluorescentes/farmacocinética , Animais , Carbocianinas/administração & dosagem , Células Cultivadas , Difusão , Corantes Fluorescentes/administração & dosagem , Processamento de Imagem Assistida por Computador , Microscopia de Fluorescência por Excitação Multifotônica , Miócitos de Músculo Liso/metabolismo , Pressão , Suínos
15.
J Biomech Eng ; 135(6): 61008-11, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23699720

RESUMO

Drug-eluting stents have a significant clinical advantage in late-stage restenosis due to the antiproliferative drug release. Understanding how drug transport occurs between coronary arterial locations can better help guide localized drug treatment options. Finite element models with properties from specific porcine coronary artery sections (left anterior descending (LAD), right (RCA); proximal, middle, distal regions) were created for stent deployment and drug delivery simulations. Stress, strain, pore fluid velocity, and drug concentrations were exported at different time points of simulation (0-180 days). Tests indicated that the highest stresses occurred in LAD sections. Higher-than-resting homeostatic levels of stress and strain existed at upwards of 3.0 mm away from the stented region, whereas concentration of species only reached 2.7 mm away from the stented region. Region-specific concentration showed 2.2 times higher concentrations in RCA artery sections at times corresponding to vascular remodeling (peak in the middle segment) compared to all other segments. These results suggest that wall transport can occur differently based on coronary artery location. Awareness of peak growth stimulators and where drug accumulation occurs in the vasculature can better help guide local drug delivery therapies.


Assuntos
Vasos Coronários/metabolismo , Análise de Elementos Finitos , Preparações Farmacêuticas/metabolismo , Stents , Animais , Transporte Biológico , Elasticidade , Cinética , Suínos
16.
Neuromodulation ; 15(6): 527-36, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22551486

RESUMO

OBJECTIVE: Electrical stimulation of the vagus nerve at relatively high voltages (e.g., >10 V) can induce bronchoconstriction. However, low voltage (≤2 V) vagus nerve stimulation (VNS) can attenuate histamine-invoked bronchoconstriction. Here, we identify the mechanism for this inhibition. METHODS: In urethanea-nesthetized guinea pigs, bipolar electrodes were attached to both vagus nerves and changes in pulmonary inflation pressure were recorded in response to i.v. histamine and during VNS. The attenuation of the histamine response by low-voltage VNS was then examined in the presence of pharmacologic inhibitors or nerve ligation. RESULTS: Low-voltage VNS attenuated histamine-induced bronchoconstriction (4.4 ± 0.3 vs. 3.2 ± 0.2 cm H(2) O, p < 0.01) and remained effective following administration of a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester, and after sympathetic nerve depletion with guanethidine, but not after the ß-adrenoceptor antagonist propranolol. Nerve ligation caudal to the electrodes did not block the inhibition but cephalic nerve ligation did. Low-voltage VNS increased circulating epinephrine and norepinephrine without but not with cephalic nerve ligation. CONCLUSION: These results indicate that low-voltage VNS attenuates histamine-induced bronchoconstriction via activation of afferent nerves, resulting in a systemic increase in catecholamines likely arising from the adrenal medulla.


Assuntos
Broncoconstrição/fisiologia , Catecolaminas/sangue , Estimulação do Nervo Vago , Nervo Vago/fisiologia , Acetilcolina/farmacologia , Adrenérgicos/farmacologia , Animais , Biofísica , Pressão Sanguínea/efeitos dos fármacos , Broncoconstrição/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Ensaio de Imunoadsorção Enzimática , Epinefrina/sangue , Guanetidina/farmacologia , Cobaias , Histamina/farmacologia , Ligadura/métodos , NG-Nitroarginina Metil Éster/farmacologia , Norepinefrina/sangue , Propranolol/farmacologia , Vasodilatadores/farmacologia
17.
N Z Med J ; 135(1566): 11-21, 2022 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-36455176

RESUMO

AIMS: Burnout and fatigue are common in the medical profession. The primary aim was to assess rates of burnout in trainee and non-trainee orthopaedic registrars in New Zealand. A secondary aim was to establish which specific factors are associated with burnout. METHODS: In 2021, a 53-question online survey was sent to New Zealand trainee and non-trainee orthopaedic registrars. The survey included questions addressing demographics, modifiable factors known to lead to burnout, information on respective orthopaedic departments, and how respondents had fared with COVID-19. Registrars also completed the Maslach Burnout Inventory-Human Services Survey for Medical Personnel (MBI-HSS MP), a 22-question validated survey that is designed to assess the frequency and intensity of perceived burnout among medical personnel. RESULTS: Fifty of 62 (80.6%) trainees and 66 of 70 (estimated number) (94.3%) of non-trainees completed the survey. Trainees and non-trainees both exhibited moderate levels of burnout. The trainee mean score emotional exhaustion (EE) 22.5, depersonalisation (DP) 8.8, personal achievement (PA) 35.9; non-trainee mean score EE 22.4, DP 8.9, PA 35.9. Fifty-two point two percent of trainees and 50% of non-trainees scored in the severe range for at least one of EE or DP. Factors shown to reduce burnout are the presence of a senior colleague (P<0.001), participation in professional assistance (P=0.049), working in a department with a full complement of staff (P=0.020) and being able to attend health maintenance appointments (P=0.050). CONCLUSION: Our study shows that approximately half of both trainee and non-trainee orthopaedic registrars are exhibiting signs of burnout. This is comparable to other developed nations with a similar healthcare system.


Assuntos
COVID-19 , Ortopedia , Humanos , Nova Zelândia/epidemiologia , COVID-19/epidemiologia , Esgotamento Psicológico , Pessoal de Saúde
19.
Front Neurol ; 13: 897124, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35911909

RESUMO

Since the outbreak of the COVID-19 pandemic, races across academia and industry have been initiated to identify and develop disease modifying or preventative therapeutic strategies has been initiated. The primary focus has been on pharmacological treatment of the immune and respiratory system and the development of a vaccine. The hyperinflammatory state ("cytokine storm") observed in many cases of COVID-19 indicates a prognostically negative disease progression that may lead to respiratory distress, multiple organ failure, shock, and death. Many critically ill patients continue to be at risk for significant, long-lasting morbidity or mortality. The human immune and respiratory systems are heavily regulated by the central nervous system, and intervention in the signaling of these neural pathways may permit targeted therapeutic control of excessive inflammation and pulmonary bronchoconstriction. Several technologies, both invasive and non-invasive, are available and approved for clinical use, but have not been extensively studied in treatment of the cytokine storm in COVID-19 patients. This manuscript provides an overview of the role of the nervous system in inflammation and respiration, the current understanding of neuromodulatory techniques from preclinical and clinical studies and provides a rationale for testing non-invasive neuromodulation to modulate acute systemic inflammation and respiratory dysfunction caused by SARS-CoV-2 and potentially other pathogens. The authors of this manuscript have co-founded the International Consortium on Neuromodulation for COVID-19 to advocate for and support studies of these technologies in the current coronavirus pandemic.

20.
J Trauma ; 69(1): 211-4, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20622592

RESUMO

Trauma during pregnancy has presented very unique challenges over the centuries. From the first report of Ambrose Pare of a gunshot wound to the uterus in the 1600s to the present, there have existed controversies and inconsistencies in diagnosis, management, prognostics, and outcome. Anxiety is heightened by the addition of another, smaller patient. Trauma affects 7% of all pregnancies and requires admission in 4 of 1000 pregnancies. The incidence increases with advancing gestational age. Just over half of trauma during pregnancy occurs in the third trimester. Motor vehicle crashes comprise 50% of these traumas, and falls and assaults account for 22% each. These data were considered to be underestimates because many injured pregnant patients are not seen at trauma centers. Trauma during pregnancy is the leading cause of nonobstetric death and has an overall 6% to 7% maternal mortality. Fetal mortality has been quoted as high as 61% in major trauma and 80% if maternal shock is present. The anatomy and physiology of pregnancy make diagnosis and treatment difficult.


Assuntos
Complicações na Gravidez/diagnóstico , Ferimentos e Lesões/diagnóstico , Cesárea , Feminino , Idade Gestacional , Humanos , Gravidez , Complicações na Gravidez/terapia , Ferimentos e Lesões/complicações , Ferimentos e Lesões/terapia
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